The present invention relates to guidewires for medical devices, and particularly to exchange guidewires for endoscopic devices.
During certain endoscopic procedures an exchange guidewire is threaded through a lumen or open channel in the endoscope. The guidewire is then maneuvered into place within a bodily passage to act as a guide for positioning of medical catheter devices to perform the procedure. Exchange guidewires are known that have a flexible coil fixedly attached to one end of a core wire to aid the maneuvering of the wire into the bodily passage, and a low-friction Teflon.RTM. sleeve covering the wire/coil combination.
Examples of an endoscopic medical procedure in which such a guidewire may be used are endoscopic surgery or other medical treatment within the common bile duct, the cystic duct, the pancreatic duct, or the left or right hepatic duct. The endoscope is introduced orally and maneuvered through the alimentary canal into the duodenum. The guidewire is threaded through the endoscope lumen and manipulated by torquing, pushing, and pulling to cannulate the papilla and to enter the common bile duct and, if necessary, any duct branching therefrom. The position of the guidewire is confirmed fluoroscopically. Typically, the flexible coil is formed from a radiopaque material to aid fluoroscopic viewing of the guidewire position. After positioning of the guidewire within the duct, a catheter bearing a medical instrument is threaded onto the exposed end of the guidewire and maneuvered through the endoscope, along the guidewire, and into position within the duct to be treated. If necessary, a sphincter tome may be threaded onto the guidewire to cut the sphincter muscle and enlarge the papilla before the guidewire enters the papilla. The guidewire, the medical instrument catheter, and the area near the papilla all are illuminated by a fiber optic light source within the endoscope and may be viewed through the endoscope using a fiber optic lens.
When a second instrument is required to perform the medical procedure, the first catheter must be withdrawn and the replacement catheter bearing the next required instrument is threaded onto the guidewire and maneuvered into position. This "exchange" process is carried out with each successive instrument needed to perform the procedure. The endoscopic system using an exchange guidewire to guide each instrument catheter into position has greatly simplified endoscopic surgery and other endoscopic procedures.
There is, however, a tendency for the guidewire to be displaced during the withdrawal of a catheter. Because such movement is not readily discerned endoscopically, the surgeon has been required to confirm the correct positioning of the guidewire tip using fluoroscopy before introducing each new instrument catheter. This can result in increased procedure time and in additional exposure of the patient and medical staff to radiation.
It would be desirable, for certain endoscopic procedures, to have a way to visually discern displacement of the guidewire during the exchange process without the use of further fluoroscopy. The exchange guidewires described herein were developed to address that need.